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(#) When using `setHasFixedSize()` in an `RecyclerView`, `wrap_content` cannot be used as a value for `size` in the scrolling direction.

!!! ERROR: When using `setHasFixedSize()` in an `RecyclerView`, `wrap_content` cannot be used as a value for `size` in the scrolling direction.
   This is an error, and is also enforced at build time when
   supported by the build system. For Android this means it will
   run during release builds.

Id
:   `InvalidSetHasFixedSize`
Summary
:   When using `setHasFixedSize()` in an `RecyclerView`, `wrap_content` cannot be used as a value for `size` in the scrolling direction.
Severity
:   Fatal
Category
:   Correctness
Platform
:   Android
Vendor
:   Android Open Source Project
Identifier
:   androidx.recyclerview
Feedback
:   https://issuetracker.google.com/issues/new?component=460887
Min
:   Lint 8.0 and 8.1
Compiled
:   Lint 8.0 and 8.1
Artifact
:   [androidx.recyclerview:recyclerview](androidx_recyclerview_recyclerview.md.html)
Since
:   1.2.0
Affects
:   Kotlin and Java files and resource files
Editing
:   This check can *not* run live in the IDE editor
Implementation
:   [Source Code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/recyclerview/recyclerview-lint/src/main/java/androidx/recyclerview/lint/InvalidSetHasFixedSizeDetector.kt)
Tests
:   [Source Code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/recyclerview/recyclerview-lint/src/test/java/androidx/recyclerview/lint/InvalidSetHasFixedSizeTest.kt)
Copyright Year
:   2020

When a RecyclerView uses `setHasFixedSize(...)` you cannot use
`wrap_content` for  size in the scrolling direction.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
com/example/Example.kt:10:Error: When using `setHasFixedSize() in an
RecyclerView, wrap_content cannot be used as a value for size in the
scrolling direction. [InvalidSetHasFixedSize]
    recyclerView?.setHasFixedSize(true)
    -----------------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here are the relevant source files:

`layout/recycler_view.xml`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers
&lt;?xml version="1.0" encoding="utf-8"?&gt;
                &lt;androidx.recyclerview.widget.RecyclerView
                    xmlns:android="http://schemas.android.com/apk/res/android"
                    android:id="@+id/my_recycler_view"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"/&gt;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`com/example/R.kt`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers
package com.example

object R {
    object id {
        const val my_recycler_view = 0
    }
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`com/example/Example.kt`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers
package com.example

import android.view.View
import androidx.recyclerview.widget.RecyclerView

class Example {
    fun main() {
        val view: View = TODO()
        val recyclerView = view.findViewById<RecyclerView>(R.id.my_recycler_view)
        recyclerView?.setHasFixedSize(true)
    }
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/recyclerview/recyclerview-lint/src/test/java/androidx/recyclerview/lint/InvalidSetHasFixedSizeTest.kt)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `InvalidSetHasFixedSizeDetector.testInCorrectUsageOfFixedSize`.
To report a problem with this extracted sample, visit
https://issuetracker.google.com/issues/new?component=460887.

(##) Including

!!!
   This is not a built-in check. To include it, add the below dependency
   to your project.

```
// build.gradle.kts
implementation("androidx.recyclerview:recyclerview:1.4.0-rc01")

// build.gradle
implementation 'androidx.recyclerview:recyclerview:1.4.0-rc01'

// build.gradle.kts with version catalogs:
implementation(libs.recyclerview)

# libs.versions.toml
[versions]
recyclerview = "1.4.0-rc01"
[libraries]
# For clarity and text wrapping purposes the following declaration is
# shown split up across lines, but in TOML it needs to be on a single
# line (see https://github.com/toml-lang/toml/issues/516) so adjust
# when pasting into libs.versions.toml:
recyclerview = {
    module = "androidx.recyclerview:recyclerview",
    version.ref = "recyclerview"
}
```

1.4.0-rc01 is the version this documentation was generated from;
there may be newer versions available.

[Additional details about androidx.recyclerview:recyclerview](androidx_recyclerview_recyclerview.md.html).
(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Using a suppression annotation like this on the enclosing
  element:

  ```kt
  // Kotlin
  @Suppress("InvalidSetHasFixedSize")
  fun method() {
     setHasFixedSize(...)
  }
  ```

  or

  ```java
  // Java
  @SuppressWarnings("InvalidSetHasFixedSize")
  void method() {
     setHasFixedSize(...);
  }
  ```

* Using a suppression comment like this on the line above:

  ```kt
  //noinspection InvalidSetHasFixedSize
  problematicStatement()
  ```

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="InvalidSetHasFixedSize" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'InvalidSetHasFixedSize'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore InvalidSetHasFixedSize ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

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